Human eyes have around 100 million photoreceptors, each of which can pick up about ten visual events every second, so our eyes are effectively receiving a billion pieces of information each second. If you include the information pouring in from our other senses, that's a staggering quantity of data for our brains to sift through every moment of our waking lives.
If we had an infinite resource of energy by which to crunch the numbers, and an infinitely fast brain by which to make the calculations, then there would be no problem, as we could analyze every scrap of data to its fullest capacity and never miss an opportunity or be caught by a threat. But, of course, in reality, it takes time to process anything, and human brains consume a frighteningly large proportion of our body's total energy resources.
Computing pioneer Charles Babbage's brain
Public domain image
Then, Bor adds in a footnote:
Even though the human brain is a mere 2 percent of total body weight, in newborns this single organ requires a staggering 87 percent of the body's total energy. A five-year-old has a brain that greedily guzzles nearly half of all the energy the child consumes, and even in adults this figure is at least a quarter, though that proportion can rise dramatically if we've had a mentally taxing day — for instance, when studying for exams. In fact, some biologists have suggested that the energy demands and complexity of a human brain are nearing the endpoint of what is biologically possible and that if you started trying to cram even more neuronal wires into the brain, the additional miniaturization that this would entail would turn all brain signal into random noise — and the cleverest organ in the known universe would suddenly become one of the dumbest.
Of course, for those of us who believe it's less a matter of what machinery the skull houses and more a matter of how we use it, this is merely of curiosity rather than of concern.
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